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Saturday, 16 October 2021

Day 579 of self-isolation - Keyboard three fixed

Keyboard three fixed

I had to completely disassemble the keyboard, but the whole job - dissassembly and reassembly only took two hours. The problem was as I thought, the spring assembly for the U key wasn't moving freely, there was a bit of plastic scurf blocking it. 

When I tested it, the right hand ctrl key didn't work, but I don't use that key, I always use the left hand ctrl key. Because it's either ctrl-c or ctrl-v. So am I bovvered?

But after fiddling with it for a bit, I think I got it working. Anyway, job done. And this was the keyboard that I thought was most likely to be unfixable!

Now the fourth ...

I also paid a routine visit to Amersham hospital, to have an INR test. My INR was 2.4, and the ideal range is 2.5 to 3.2. It has been wobbling about a bit, and they've been chasing it around. So now instead of 6.5 mg per day, I'm on 6.5 per day and 7 on weekends. Which is 6.64, a whole 0.14 milligrams more than before, a 2% change.

While I was there, I toddled over to the blood test clinic, this is part of the investigation into why my liver ALS is so high. It isn't booze; most weeks I have none, some weeks I might have a bottle of beer.

They saw me immediately, took a couple of vials of blood out of my arm, gave me a bit of cotton wool, and I was done.

So I visited the bookshop on my way out, and treated myself to four books, while at the same time helping the scanner fund.

Then, fours hours later, I went back for my ultrasound scan. I lay on my back while a nice nurse tickled me and eventually told me that she'd found nothing of interest. So I bought four more books. This is why paper books are better than e-books. I can buy second-hand paper books.




Friday, 15 October 2021

Day 578 of self-isolation - Keyboard three reassembled

Keyboard three reassembled

I've learned a bit more - don't bother with replacing the rivets at the front edge. Also - note which places on the keyholder, don't have a buckling spring assembly; mark with a red cross, otherwise you won't know which ones to leave empty when you reassemble.

So, I reassembled the keyboard and tested it. It worked ... except for the letter U. Clearly, I can't use a keyboard that is missing the U, although I can create a U using the alt key and the numeric keypad, but that's  clumsy.

I think the problem would be that during the reassembly, I didn't get that bucking spring assembly right. So, I'll have to dismantle the keyboard and try again

The original problem that this keyboard had, is solved. I think it was the mess on the plastic sheets

It'll be much easier second time around - no chiselling or drilling required, and no washing. Also, I've been gradually collecting tools to make the job easier. Plus, practice makes things easier.

I'll use "showkey -k" to test the keys. Also the grey + key on my main workstation keyboard wasn't working. I took off the keycap, and prodded the bucking spring assembly with a plastic prodder, replaced the keycap, and now it's working!



Thursday, 14 October 2021

Day 577 of self-isolation - Keyboard three, 13:11

Keyboard three

With the recent experience of fixing keyboard 1 and 2, I turned my attention to keyboard three. The problem there is that all the keys work, but some of them add extra characters, such as a #. I can't imagine what could be causing this, but let's have a look inside.

I took off the outer beige shell, took off the keycaps (and put them to soak in water with a bit of detergent - some of them were very dirty) then turned it over. I balanced the assembly on two dead hard drives to keep it steady, then selected one of my new chisels (1/2 inch) and a mallet. It turns out that this is a MUCH easier way to cut the heads off the plastic rivets than the way I did it before. So I was soon able to separate the black plastic keyholder from the steel backplate.

The plastic sheets holding the traces were really dirty; I scrubbed them with a soft brush and some detergent, and left them to dry. When they were dry, I checked all the contacts for continuity, and they worked fine - no silver paste needed.

Then I started drilling. I'm using the Dremel now, and it's much better than the big drill in the stand. I got a chuck from eBay that lets me put small drills on the Dremel. The drill got clogged up with plastic every few holes; I scraped it off with a Stanley knife.

A 1/16 drill bit from the Dremel, then I'm using a 3/32 bit in an electric screwdriver to widen the hole slightly, so that the bolt goes in more easily.  I've drilled all the 57 holes, and checked that the bolt and nut will work.

All the keycaps are clean now, and I'm leaving them out to dry.

The steel backplate was rusty in places, so I wire brushed it until it was clean with the Dremel.  And some rust had leaked into the plastic sheets, and maybe that's the cause of the problem? At some point, this keyboard must have had water inside. We'll see after I do the reassembly.

And I'm down to 13:11; BMI = 27




Wednesday, 13 October 2021

Day 576 of self-isolation - Keyboard fixed!

Keyboard fixed!

The model M IBM keyboard that I've been working on, is fixed. I tightened all the nuts and bolts, reassembled the keyboard, and plugged it into a computer. I checked all the keys and they all work!

I have learned a lot about how to do this repair. I have three more keyboards that need attention.

So, in summary. Remove the outer white plastic shell, and remove all the keycaps. Then use a chisel or a grinder to cut the heads of the plastic rivets,and pull the keyboard apart, separating the black plastic keyholder from the steel backplate. Remove the four sheets inside.

Remove the buckling springs. Now all the bucking springs, and all the key caps, can be cleaned, in a dilute solution of detergent. All you need to do is soak them.

Use a 1/16 drill to drill from the holes in the steel backplate though the black plastic keyholder. Then line up these two, and see if you can probe from front to back with a fine screwdriver or similar. At that point, I think it's a good idea to enlarge the hole to 1/8 using a slow drill, and at the same time, improve the lineup of the holes in the steel and the black plastic. Eventually, is should be possible to bolt the two together with all the bolts - but it might be necessary to do a bit more drilling to get the lineups right.

Test the two plastic sheets with traces, to ensure connectivity between the thing that plugs into the electronics, and all the places on the sheet that is should connect to. I would expect something like 25 to 50 ohms resistance, but 90 ohms is OK. If there is a break, repair it with silver or graphite paste (silver is better, but graphite is cheaper). When the paste is dry, check it again (the paste isn't conductive until it is thoroughly dry).

When everything is properly dry, reassembly can start. First you put the bucking spring assemblies into place, then you put the plastic sheets over that, then the rubber sheet, then the steel backplate. You'll need to do all that without inverting what you're working on, because if you do, the buckling spring assemblies come loose, you won't realise it, and the keyboard won't work when it's reassembled. I found that a useful test is to wiggle the keyboard slightly, and check that the springs also wobble.

So doing up the first few screws is difficult, because you're working upside down, but after you have a few in place, you can turn it over and work from there.

I'm using phillips head bolts. And although everyone says you need washers, I found that if you tried to use a washer, then the bolts wouldn't be long enough to reach the nut. At the front of the keyboard, you don't want a length of bolt sticking out, because that will stop you from putting the keyboard assembly into the white plastic back. 

If the space bar, or one of the other big keys goes down by doesn't come up again, a touch of oil can help. And then I say a touch, I mean a lot less than a drop. I put a drop on a piece of plastic, then use a fine screwdriver to pick up a touch of oil and put it where needed.

My second faulty keyboard, is just a bit hesitant on the space bar. Now that I've seen inside the first keyboard, I don't think dismantling it is the way to go. So I took out the space bar, and put a touch of oil in the right places, and now it's a bit better.

So - on to the third faulty keyboard ...




Tuesday, 12 October 2021

Day 575 of self-isolation - Keyboard - second try

Keyboard - second try

I removed most of the keycaps so that I could see the bolt heads, then I removed the nuts holding the keyboard together. It was a mistake not to remove all the keycaps, because the keycaps that were in place, made the buckling spring parts come out of their places.

I tested the traces for continuity again, and they were all fine. So I thnk that the problem had been that the buckling spring parts hadn't been seated properly.

I reassembled the layers of the keyboard, but soon found that some of the buckling spring parts had come out of their seatings. So I took it apart again, reseated the buckling spring parts and, without turning the keyboard over, reassembled the layers and put in some of the nuts and bolts.

I think that the test to do then, is to turn the keyboard over so that the buckling spring parts are uppermost, and then shake it slightly to check that they all move freely.

So I put in all the bolts and nuts. The next thing, tomorrow, will be to tighten up all the nuts (I've just bought a 4mm spanner from Hobbyking) and see if everything works.

Here are pictures of the traces. As you can see, the wide connector connects to lines of traces that go up and down, while the narrow connector connects to lines that go from side to side. 

Pressing a key, should bring one of the white blobs in the upper picture, into contact with one of the white blobs in the lower picture. The connectors go to a small electronics board, and that knows (by seeing which connectors are connected via the keypress) which key has been pressed, and it translates tat to a scan code that it sends to the computer. Very clever.

You can see in the lower picture where I painted conductive graphite to repair three breaks in the lines. I think those breaks were caused by the water spill that started this whole repair job off.

The egg whisk that you see in the top right hand corner of the picture. is actually the key puller, and it does that job splendidly.








Monday, 11 October 2021

Day 574 of self-isolation - Jaunt to London

Jaunt to London

Another trip to London. On the way there, we noticed that each of the petrol stations we passed had a few people filling up and no queues. And in the evening, we saw a tanker filling up a forecourt.

So the petrol crisis looks to be over.

 

 


Sunday, 10 October 2021

Day 573 of self-isolation - Thirteen stone, twelve pounds

Thirteen stone, twelve pounds

Yes, another pound less. 194 pounds, 88 kilograms. Still going down.

Also, on the keyboard. I tried tightening up the nuts and bolts that hold it together. I didn't think it would work, but there was the possibility that it would, and it was an easier thing to try than to dismantle and look at the insides.

It didn't work.

So, the next step will be to undo those 57 nuts and see if I can work out why those keys aren't working.